The present invention relates to a method and an apparatus for winding a strand of glass fiber filaments onto a takeup collet in a glass fiber takeup machine when the glass fiber filaments are drawn off from nozzles.
When a strand of glass fiber filaments starts being drawn in a glass fiber takeup machine, it has been customary practice to wind the strand of glass fiber filaments on a takeup collet by manually catching the leading end of the strand and winding the same around the collet being rotated while tensioning the strand at the same time. More specifically, in drawing off glass fiber filaments, melted glass is drawn as a number of fiber filaments from a bushing, and wound on the collet in the takeup machine after having passed through an application roller and a gathering roller. The bushing and the takeup machine are spaced widely apart from each other; usually, the bushing is located on the second floor of a building, while the takeup machine is installed on the first floor. The conventional takeup process has required a cooperation between two workers, one on the second floor for drawing the glass fiber filaments off from the bushing, and the other on the first floor for catching and winding the end of the glass fiber filaments onto the collet. The conventional method involves manual work, demands skilled operation, places a large amount of burden on the workers, and is difficult to achieve a desired degree of safety during operation.
On the other hand, in general, elongated glass fibers are normally fabricated by drawing a multiplicity of filaments from a bushing having a number of nozzles, applying sizing agents to the filaments, and collecting the filaments as one or more strands. The strand is then wound for a constant quantity at a fixed rate in the range of from 1,500 to 5,000 m/min. onto the periphery of the collet which rotates a few thousand revolutions per minute so that the strand is given a predetermined degree of elongation and composed of a few hundred to thousand filaments gathered each of a diameter ranging from 3 to 20 microns.
A full bobbin on which the strand is wound in a given quantity is removed from the collet, and then an empty bobbin of paper or film is fitted onto the collet for winding the strand thereon, an operation which is effected intermittently, whereas the glass filaments flow out of the bushing uninterruptedly. Various means have been proposed and put to use which include a rotatable table or a reciprocating table for displacing two or three collets alternately into a winding position, a full bobbin unloading position, and an empty bobbin loading position to effect quick bobbin switching and winding, while rejecting larger-diameter filament portions as waste strands which are produced when the speed of feed of the strand is increased to a constant winding speed after the strand has been stopped, or when the speed of feed is reduced from the constant winding speed. Expressed in another way, during initial and final periods of winding operation in which the strand is wound at a speed lower than the fixed rate, the filaments are larger in diameter than desired due to a reduced degree of elongation and hence should be rejected as waste strands. Various means have been put to use for removing such waste strands. The means for rejecting the waste strands normally include an auxiliary winder mounted on a free end of the takeup collet, or an auxiliary winder separate from the takeup collet so as to be independent of a normal winding section. The former means requires that the waste strand be cut off and removed when a fully wound bobbin is to be detached from the collet, resulting in an increased collet changing time. Both of the means need operator's manual intervention for initial strand winding and full collet interchange, and for this reason are subjected to less reliability and safety.
Also, the strand drawn off after accidentally broken off has conventionally been wound manually onto a collet, and then normally wound thereon via a traversing device when the collet reaches a predetermined speed of rotation thereof, with a strand portion which has been wound at a slow rate in an initial stage being cut off and removed as a waste strand of a different diameter.
Furthermore, the foregoing winding operation is intermittent in that when the strand is fully wound on a collet, the strand is moved outside of a winding zone, and another collet with an empty bobbin is brought into the winding position in which it starts rotating, with the strand that flows along a path outside of the winding zone being manually caught on and wound around the new collet.
Therefore, the strand portion that has been wound during a period other than the normal winding at the predetermined high speed is discharged as a waste strand. It is also important that the length of waste strand be reduced as much as possible for an improved efficiency of glass fiber spinning.